Organopolysiloxane Dielectric Layer Composition for Low-Modulus Transducers
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Solution Overview
Problem
Existing curable organopolysiloxane compositions for transducers do not provide a cured product with a low storage modulus over a broad frequency range and low loss tangent, lacking favorable reversion characteristics after deformation by external stresses.
Innovation Solution
A curable organopolysiloxane composition comprising straight chain or branched chain organopolysiloxanes with a weight-average molecular weight less than 8.0×104, a SiH/Vi ratio of less than 1, and a specific crosslink density parameter (Mw(a)/px1) in the range of 1,000 to 8,000, along with a hydrosilylation reaction catalyst, reinforcing filler, and adhesion promoting agent, to achieve a low storage modulus and low loss tangent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional curable organopolysiloxane compositions are used, then mechanical strength and dielectric properties are achieved, but storage modulus is high and reversion characteristics after deformation are poor
Solution Approach 1:
The patent changes the molecular weight parameter (Mw < 8.0×10^4) and crosslink density parameter (Mw/px1 in 1000-8000 range) of the organopolysiloxane composition to achieve a balance between mechanical strength and low storage modulus. This parameter optimization allows the cured product to maintain adequate strength while exhibiting low storage modulus across a broad frequency range, thereby improving reversion characteristics after deformation.
2Strength
If crosslink density is increased to improve mechanical properties, then strength is improved, but storage modulus increases and reversion characteristics deteriorate
Solution Approach 1:
The patent optimizes the crosslink density parameter px1 and the molecular weight Mw to achieve an optimal balance. By controlling the ratio Mw/px1 within 1000-8000, the composition achieves sufficient crosslinking for mechanical strength while preventing excessive crosslinking that would increase storage modulus. This delicate parameter control enables simultaneous achievement of strength and low storage modulus.
Solution Approach 2:
The patent employs a composite approach by combining organopolysiloxane with specific molecular weight and crosslink density characteristics. The composition integrates multiple functional aspects: the polysiloxane backbone provides mechanical strength, while the controlled crosslink density ensures low storage modulus. This composite structure at the molecular level resolves the contradiction between strength and reversion characteristics.
3Strength
If molecular weight is increased to improve mechanical strength, then strength is improved, but reversion characteristics after deformation worsen
Solution Approach 1:
The patent sets a specific upper limit for molecular weight (Mw < 8.0×10^4) to maintain reversion characteristics. By controlling Mw within this range and optimizing the Mw/px1 ratio, the composition achieves adequate mechanical strength from the polysiloxane chains while preventing excessive chain length that would hinder reversion. This parameter constraint ensures that chains are long enough for strength but not so long as to compromise elastic recovery.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composition yields a cured product with excellent electrical properties, low storage modulus, and favorable reversion characteristics, suitable as a dielectric layer for transducers, particularly in film-like or sheet-like transducers.
Implementation Method 1
a curable organopolysiloxane composition comprising straight chain or branched chain organopolysiloxanes... an organohydrogenpolysiloxane... and a hydrosilylation reaction catalyst
Implementation Method 2
a hydrosilylation reaction catalyst
Implementation Method 3
has low storage modulus over a broad frequency range, has low loss tangent properties, and has viscoelastic properties that are particularly suitable as a dielectric layer
Data Source
AI summary
Provided is a curable organopolysiloxane composition that yields an organopolysiloxane cured product having viscoelastic properties (particularly, reversion characteristics after deformation due to external stress) that are particularly suitable for use as a dielectric layer or a transducer, and a method of use thereof. A curable organopolysiloxane composition for transducers, contains: (a) a chain organopolysiloxane or mixture thereof having a weight-average molecular weight (Mw(a)) of less than 8.0×104; (b1) a crosslinking agent; (b2) a chain length extender; and (c) a hydrosilylation reaction catalyst. The molar quantity of Si—H (Hb1, Hb2) in component (b1) and component (b2) and the molar quantity of curable reactive groups (Vi) in component (a), satisfy the following relationship: px1={Hb1/Hb2}/{(Hb1+Hb2)/Vi}; where the value obtained by dividing Mw(a) by the value of px1, i.e., Mw(a)/px1, is in a range of 1,000 to 8,000.